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9,253 diagnostic guides

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Find codes by symptomChoose what you notice to search matching code guides.

Rough idle or shakingVibration while stopped Hard to startLong cranking or no-start Engine stallsCuts out at idle or on the road Hesitates or loses powerSlow response when accelerating Battery light is onCharging system warning Harsh gear changesDelayed or rough shifting

A symptom can have several causes. Treat matching codes as clues and follow the diagnostic checks in each guide.

Check soon P · Powertrain Clear all

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Engine1049 Emissions515 Fuel1016 Sensors & Electronics2110 Transmission866 Electrical & Charging1797 Body & Restraints193 Chassis & Brakes479 Network & Communication1228

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All severities9253 Low priority305 Check soon8256 Urgent621

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All families9253 P · Powertrain7353 B · Body193 C · Chassis479 U · Network1228

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These are generic OBD2 definitions. Exact make, model, engine, and year compatibility will appear after vehicle-fitment data is added.

Diagnostic codes

Showing 3505–3528 of 6682

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P21BCCold Start Cylinder 7 Injection TimingCheck soonFuel System30–120 minutes for initial diagnosisP21BC relates to cold start cylinder 7 injection timing. Check the fault conditions and vehicle-specific procedure before replacing parts.P21BDCold Start Cylinder 8 Injection TimingCheck soonFuel System30–120 minutes for initial diagnosisP21BD relates to cold start cylinder 8 injection timing. Check the fault conditions and vehicle-specific procedure before replacing parts.P21BECold Start Cylinder 9 Injection TimingCheck soonFuel System30–120 minutes for initial diagnosisP21BE relates to cold start cylinder 9 injection timing. Check the fault conditions and vehicle-specific procedure before replacing parts.P21BFCold Start Cylinder 10 Injection TimingCheck soonFuel System30–120 minutes for initial diagnosisP21BF relates to cold start cylinder 10 injection timing. Check the fault conditions and vehicle-specific procedure before replacing parts.P21C0Cold Start Cylinder 11 Injection TimingCheck soonFuel System30–120 minutes for initial diagnosisP21C0 relates to cold start cylinder 11 injection timing. Check the fault conditions and vehicle-specific procedure before replacing parts.P21C1Cold Start Cylinder 12 Injection TimingCheck soonFuel System30–120 minutes for initial diagnosisP21C1 relates to cold start cylinder 12 injection timing. Check the fault conditions and vehicle-specific procedure before replacing parts.P21C2Reductant Heater Relay Control Circuit/OpenCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP21C2 relates to reductant heater relay control circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P21C3Reductant Heater Relay Control Circuit LowCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP21C3 relates to reductant heater relay control circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P21C4Reductant Heater Relay Control Circuit HighCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP21C4 relates to reductant heater relay control circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P21C5Reductant Level Sensor A StuckCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21C5 relates to reductant level sensor a stuck. Check the fault conditions and vehicle-specific procedure before replacing parts.P21C6Reductant Level Sensor B StuckCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21C6 relates to reductant level sensor b stuck. Check the fault conditions and vehicle-specific procedure before replacing parts.P21C7Reductant Control Module Power Relay/Relays Control Circuit/OpenCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP21C7 relates to reductant control module power relay/relays control circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P21C8Reductant Control Module Power Relay/Relays Control Circuit LowCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP21C8 relates to reductant control module power relay/relays control circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P21C9Reductant Control Module Power Relay/Relays Control Circuit HighCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP21C9 relates to reductant control module power relay/relays control circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P21CAReductant Control Module Supply Voltage CircuitCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP21CA relates to reductant control module supply voltage circuit. Check the fault conditions and vehicle-specific procedure before replacing parts.P21CBReductant Control Module Supply Voltage LowCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP21CB relates to reductant control module supply voltage low. Check the fault conditions and vehicle-specific procedure before replacing parts.P21CCReductant Control Module Supply Voltage HighCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP21CC relates to reductant control module supply voltage high. Check the fault conditions and vehicle-specific procedure before replacing parts.P21CDReductant Quality Module Supply Voltage LowCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP21CD relates to reductant quality module supply voltage low. Check the fault conditions and vehicle-specific procedure before replacing parts.P21CEReductant Quality Module PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21CE relates to reductant quality module performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P21CFCylinder 1 Injector B Circuit/OpenCheck soonFuel System30–120 minutes for initial diagnosisP21CF relates to cylinder 1 injector b circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P21D0Cylinder 2 Injector B Circuit/OpenCheck soonFuel System30–120 minutes for initial diagnosisP21D0 relates to cylinder 2 injector b circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P21D1Cylinder 3 Injector B Circuit/OpenCheck soonFuel System30–120 minutes for initial diagnosisP21D1 relates to cylinder 3 injector b circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P21D2Cylinder 4 Injector B Circuit/OpenCheck soonFuel System30–120 minutes for initial diagnosisP21D2 relates to cylinder 4 injector b circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P21D3Cylinder 5 Injector B Circuit/OpenCheck soonFuel System30–120 minutes for initial diagnosisP21D3 relates to cylinder 5 injector b circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.